The present invention relates to a disposable diaper that can be put on a wearer with ease whether the portion having fastening tapes (hereinafter referred to as a first section) goes in either the front or the back of the wearer and which hardly leaks when put on in either way.
Known disposable diapers include fitted diapers having fastening tapes and pull-on diapers (also called pants type diapers or all-in-ones) that can be put on like ordinary underwear. Fitted disposable diapers are most commonly used in view of their applicability to a full range of children, from newborns to toddlers, and because of their lower production cost. Fitted disposable diapers are generally designed such that the portion with fastening tapes (back portion) is placed in the back and the fastening tapes are fastened from the back onto a landing zone on the front portion to hold the diaper on securely.
This way of diapering, i.e., a back-to-front way of fastening, is easy on such a wearer as a baby or an infant lying still on its back. However, it is not easy on an infant who is active enough to, for example, crawl or roll, being reluctant to wear a diaper.
Pull-on disposable diapers are on the market for infants who can walk, but disposable diapers suited for babies who have mastered crawling and are now on to pulling themselves up are not available yet. Even after a baby becomes able to pull itself up on something into a standing position, it is practically difficult to make the baby raise one foot to put on a pull-on diaper.
Hence, the present inventors have attempted to use a conventional fitted disposable diaper backward, that is, put on the diaper with back portion going in the front. However, when a conventional fitted disposable diaper, which is designed for back-to-front fastening, is put on backward, it is less capable of exhibiting its absorbing ability and more liable to leak while worn than when put on in a normal back-to-front way. Moreover, a conventional fitted diaper designed for back-to-front diapering is difficult to put on backward.
JP-A-6-63077 proposes a disposable diaper which is designed to be fastened with fastening tapes on the wearer's back side. The diaper has an elastic flap on each side of the stomach portion and a fastening tape fixed to each of the elastic flaps and enjoys ease of fastening on the wearer's back side as compared with traditional fitted disposable diapers. Nevertheless one often finds it convenient to fix fastening tapes on the wearer's front side. Therefore a diaper configured exclusively for fastening on the back side cannot avoid sacrificing for ease of putting on the front side, both absorbing front side). The diaper of JP-A-6-63077 is designed for fastening only on the wearer's back side for application to infants who have developed to move actively and therefore gives no considerations to back-to-front fastening usage. Thus, a disposable diaper that sufficiently satisfies ease of putting on and absorption requirement when fastened on either way has not yet been proposed.
Fitted disposable diapers having a pair of extensible side parts are recently known as being easy to fasten on the stomach side, the extensible side parts each having a plurality of elastic members and being arranged on the inner side of each fastening tape. This type of disposable diapers give a snug fit as long as they are fastened on the stomach side. However, when they are put on backward, it turned out that bunching or wrinkling occurs between, or in the vicinity of, the extensible side parts, which generates a gap between the wearer's body and the diaper and easily causes leakage.
JP-A-2-164363 proposes a diaper cover which is designed to be fastened with fastening tapes on the wearer's back side. The diaper cover is not provided with an absorbent member in a unitary manner, and is to be used by placing a diaper at an appropriate portion of the cover. Due to this constitution, the diaper tends to slide down from the placed position and leakage tends to occur. The fastening tape is difficult to pull, and the diapering operation is not easy in the case of back side fastening usage. Even if one fastens the fastening tape on the infant's back side with some effort, the diaper cover fails to follow the infant's movement and tends to slide down due to unconformity to the change in the waist size of the infant. Furthermore, the diaper is designed to be fastened on the wearer's back side, and no consideration is given to front side fastening usage.
WO95/12376 discloses a diaper having a pair of fastening ears which extend to the wearer's back side. Due to the constitution that the diaper is fastened on the wearer's back side, there is a fear of leakage when it is fastened on the front side. The ears largely shrink when the wearer puts on the diaper, which does not provide good diapering.